The appearance and condition of the skin may be degraded through the effects of environmental factors, either naturally occurring (sunlight, wind abrasion, humidity, etc.) or man-made (heating, air condition, pollutants, etc.), pathological processes such as dermatological diseases, or the normal aging process. The various insults to which the skin is exposed may act individually or synergistically.
To ameliorate or prevent the deterioration of skin quality that may occur over time, consumers have increasingly sought new and/or improved cosmetic compositions and cosmetic methods for skin care. Such products or methods are designed to prevent, delay or reverse the visible signs of the aging process, such as the appearance of wrinkles, lines, loss of skin tone, thinning of the skin, hyperpigmentation or mottling, and age spots. Such products or methods are further designed to improve the appearance and condition of sensitive, dry or flaky skin, and/or to soothe skin that has been irritated by exposure to chemicals, wind, or sunlight, among other potential irritants.
To meet consumer demand, many cosmetic compositions and cosmetic methods have been developed for skin care and treatment. However, many, if not most, of the products or treatment methods described to date lead to inadequate results or are marred by undesirable side effects. These may include irritation of the skin or adjacent mucous membranes, the production of excessive oiliness or greasiness of the skin, or discoloration of the skin.
Skin care products that have received considerable attention recently are those containing retinol (Vitamin A) or related compounds. Retinol, which is introduced into the body through the diet is metabolized to yield various derivatives called retinoids. Retinoids exert a variety of biological functions, including regulation of cellular proliferation, cellular differentiation and cell death. Retinoids are especially critical in the control of epithelial cell differentiation.
Natural and synthetic vitamin A derivatives (retinoids) have been used extensively in the treatment of a variety of skin disorders and have been used as skin repair or renewal agents. Retinoic acid, for example, has been employed to treat a variety of skin conditions, e.g. acne, wrinkles, psoriasis, age spots and discoloration. See e.g. Vahlquist et al., J. Invest. Dermatol. 1990; 94:496-498; Ellis et al., “Pharmacology of Retinols in Skin”, Basel, Karger, Vol. 3, (1989), pp. 249-252; Lowe et al., “Pharmacology of Retinols in Skin”, Vol. 3, (1989), pp. 240-248, PCT Patent Application No. WO 93/19743.
However, the use of products containing retinol or retinol derivatives can lead to mild side effects including but not limited to redness or stinging, itching, burning, skin scaling, peeling and dryness of the skin, or more severe side effects including but not limited to severe burning, itching, crusting, or swelling of the skin or alterations in skin pigmentation. Increased sensitivity to the environmental factors such as sunlight, wind or extremes in temperature also commonly occurs.
In light of these limitations, there continues to be a long-felt need for the development of improved cosmetic compositions and cosmetic methods for skin care and treatment that are both effective and fail to induce undesirable side effects. Toward this end, and as alternatives to products containing retinol or retinol derivatives, many researchers have examined topical anti-aging skin care compositions comprising various combinations of vitamins. For example, U.S. Published patent application Ser. No. 2002/0028844 discloses a combination of Vitamin C and Vitamin B5; U.S. Pat. No. 4,704,280 discloses a combination of Vitamin C and Vitamin B6; U.S. Pat. No. 5,541,220 discloses a combination of Vitamins C, B1, B2 and B6; related U.S. Pat. Nos. 5,652,261 and 5,786,384 disclose a combination of Vitamin C, Vitamin E, and a non-specified vitamin of the B series. Further, various combinations of Vitamin C and N-acetyl-cysteine are disclosed in U.S. Published patent application Ser. Nos. 2002/0115723, 2002/0106339, 2002/0064538, and in U.S. Pat. Nos. 5,972,999 and 6,365,630.
In contrast to the topical anti-aging skin care compositions listed above, the present invention comprises Vitamin B1, Vitamin B5, Vitamin C, N-acetyl-cysteine and, optionally, lipoic acid. When applied topically to the skin, the present invention can prevent or reverse cosmetically undesirable skin conditions such as wrinkles, lines, sagging, hyperpigmentation and age spots.